ASME-RTP 1 Balsa Wood

[nuche1973]

Greetings,
This post is to satisfy my own curiosity and there is no immediate need for an answer. I was reading through the ASME –RTP 1 and there is a section on the use of balsa wood cored plates (Part 4 Fabrication). The section gives the requirements for balsa wood laminates. My question is why balsa wood? Why not some of the harder species like oak, hickory or even pine? What special properties does balsa wood possess?

 

[SincoTC]

Its got to be weight, or lack of it to be precise!

 

[SincoTC]

Pity you can't edit posts! I forgot to add, it also has very good crush resistance when sliced up and used "End grain", this combined with its low density made it very popular for use as a core material before honeycomb style materials appeared.

 

[CoryPad]

The special property of balsa wood is mass density: 0.16 g cm^-3 vs. 0.5 to 0.8 for the other woods you listed.

 

[ornerynorsk]

Balsa is used extensively for core material in large FRP fabrications such as boat hulls. Expanded polystyrene melts in these applications, and balsa adds additional strength beyond what styrofoam is capable of.

 

[AllHandlesTaken]

Yes, as above it is due to the low weight of balsa.
While it does add some strength - the main purpose of the middle layer is just filler, to get the laminate strength away from the center (add moment of inertia). Analagous to the additional strength of a deeper wide flange beam.

 

[KENAT]

Same reason it was used on DH mosquito and the like.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[nuche1973]

Kenat,
are you refering to the airplane used in WW2?

 

[KENAT]

Yeah. Plywood with balsa filler as I recall.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[nuche1973]

Thanks for the information.